It can be a normal operating sound on some models, but a click alone cannot identify the source with certainty. Consider the usual sequence and any changed result.
Understanding this situation
A brief familiar event differs from repeated loud impacts or a dispenser that remains closed after an otherwise complete programme. Do not open a hot active dishwasher simply to watch the mechanism.
A useful next step
Use the final result and model guidance. Record the timing if the sound is new or accompanied by a problem. Avoid dismantling the dispenser or running an open-door experiment to prove what clicked.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.